on of Italians, he was born in Buenos Aires. His father was an instrumentalist, María, his elder sister, was a piano teacher and Amílcar, his youngest brother, played fagot at the Teatro Colón.

At age 8 he began to study piano with maestro Luis Romaniello, violin with Roberto Torterolo and composition with Constantino Gaito. He continued his studies at the Santa Cecilia conservatory, where he was at the same time student and pianist, accompanying on piano the students of its director, Hércules Galvani, a violin teacher.

Still a kid, he formed, with the brothers Astor Bolognini and Remo Bolognini, a classical orchestra that performed for three years at the Palace Theatre. In 1910 the Russian ballet led by Serge Diaghilev that included the well-known dancer Nijinsky appeared at the Teatro Colón. The orchestra conductor was the famous René Bathón who then was needing an important pianist and, by chance, Castellanos was introduced to him. The former asked the latter while showing a music score: «Do you dare to play this?» - «Certainly!» —he answered calmly—. «Then, tomorrow we have a rehearsal. I’ll be waiting for you». But that evening he asked his “particella” to the person in charge of the music archives of the theater. He studied it and when the time of the rehearsal came Bathón was amazed by his facility to play at first sight. He was accepted and traveled with the company to appear in Uruguay.

In 1918, he married the concerto violinist Esther Larroque. The following year the famous Russian dancer Ana Pavlova arrived in our country. The French conductor Bathón suggested her to hire him as pianist. He backed her at the four seasons that the diva performed at the Teatro Coliseo until 1922. But he declined to continue with her in her tours of the world because he did not like to be far from his wife and her newly born daughter.

During the summer of 1922, he was pianist of the Francisco Lomuto Orchestra for stints at the Club Mar del Plata. After the season he was hired by the Max Glücksmann’s company to conduct a classical orchestra that would appear at the Grand Splendid cinema theater. It was lined up by Remo Bolognini and Juan José Castro (violins) José María Castro (cello), Martucci (flute) Alberico Spatola (clarinet) and Goldstein (trombone). In an interview for the Radiolandia magazine(1939) he said about it: «People liked the orchestra very much, even maestros and conductors of the Colón came to hear it. We used to rehearse in the afternoons to appear in the evenings. But when we rehearsed in the afternoon the audience were kids because comic films were projected. That was curious. While a Chaplin movie was seen the orchestra was rehearsing a symphony, with stops and indications in a loud voice, but the kids were concentrated on the screen as if nothing else was happening». This aggregation recorded for the Glücksmann’s label.

Five years passed, sound movies came and the days for the orchestras at the cinema theaters were over. Between 1928 and 1929, he was pianist for Francisco Canaro when Luis Riccardi was unable to do it. He played on several recordings. In 1929, he formed a tango orchestra with which he recorded for the Dacapo label. In September and up to March 1932 he was art director of the Columbia Phonograph and led the Orquesta Típica Columbia. He cut tens of recordings and had Ernesto Famá, Antonio Buglione and Jorge Omar on vocals. He also accompanied the artists of the label: Tania in 56 recordings, Virginia Vera, Roberto Maida, Libertad Lamarque and Los Trovadores de Cuyo, among others.

On March 17,1933 he played the piano, conducted and arranged for a group of ten players to back Carlos Gardel's recordings. Among others he had Washington Castro (cello) and Alfredo Citro (violin). The numbers were “Estudiante”, “Cuando tú no estás” and “Por tus ojos negros”. For the recording of the waltz “Noches de Atenas” he put together a symphonic quintet with Remo Bolognini and Hugo Mariani (violins), José María Castro (cello) and Humberto Di Tata (contrabass). Hugo Mariani was Uruguayan, he belonged to the body of orchestra conductors of the National Broadcasting Company of New York. He had arrived in our city to conduct jazz concerts but, amazed by Gardel's voice, by cable he made the N.B.C. hire him to appear in the United States. The singer accepted and asked Castellanos to be his musical advisor. The contract meant a three-month tenure. The conductor of the orchestra was Mariani and Castellanos wrote the arrangements.

In the Gardel's movies he was credited for several roles. In Cuesta abajo and El Tango en Broadway he was the musical director and accompanist in the Terig Tucci's orchestra. He backed with his piano some scenes in which Gardel sings. He was as well actor, assistant to the director Louis Gasnier, wrote the soundtracks, arranged and transcribed to music notation some melodies that Gardel whistled to him. In July 1934, Carlos recorded “Criollita decí que sí” and “Caminito soleado”. He accompanied the singer on piano along with the guitar players Miguel Cáceres and Agustín Cornejo. He was pianist for Terig Tucci in “Mi Buenos Aires querido”, “Cuesta abajo”, “Golondrinas”, “Soledad”, “Amores de estudiante” and “Rubias de New York”.

In the abovementioned interview he tells us: «The work in the movies was overwhelming and ungrateful. Those were films for export and were shot without paying attention to details. Everything was fast. We worked without rest and everybody complained, except Gardel that stood all in resignation. -«It's the only way to work with these guys.», used to say Carlitos. His aim was to get money to be able to run his own studios in Buenos Aires. That same objective guided him when he embarked on the fatal tour. «The orchestra had 25 excellent musicians but we were unable to get just a bandoneon player. I was forced to hire an accordionist to provide a little color. In New York we all lived in the same building. Those were eleven months of battle, we almost had no time to sleep, there were times when I had to wear a moustache to appear and say “good morning”, there were no extras. No one can imagine how those movies were shot. Only the great soul of Gardel was capable of encouraging us before so much selfishness and sordidness. When Cuesta abajo was premiered at the Campoamor cinema theater we almost fainted. The editors had made a disaster. The chief editor was Catalonian and when he was unable to understand a joke or a Buenos Aires expression he cut it. That was not the movie we had shot, however, it was successful».

He returned to our country to briefly visit his family because he had to go back to Europe to shoot two more films. That prevented him from being in the tragic plane.

On November 29, 1935 Radio El Mundo was opened. Since then and for many years he was connected to it as musical advisor, conductor of the staff classical orchestra and sometimes of the symphonic and the tropical orchestras. He accompanied the popular singers and was very fond of Enrique Carbel who died very young.

He was a tall, slim, bald man with a fiery temper. But he was modest, bohemian, a great talker, refined, joking and gentle. He was fond of cooking and he liked horseracing, dice, playing cards and billiards.

He composed, among others, the tangos “Ausencia”, with words by Mario César Gomila -later recorded by the Maderna's orchestra- and “Nuestra casita”, with lyric by Francisco Mitjana Corney, recorded by the Fresedo's orchestra; “Muñeca de mi corazón” and “Saudades”, with the same author; “Dulce prenda”, with lyric by Enrique Maroni; “Príncipe de Gales”, a ranchera with lyric by Luis Franco; “Viejo tiempo”, recorded by Rafael Canaro in Paris, and many more. A zamba with lyrics by Le Pera: “Mis amores” was never released.

He fell ill and for two years he withdrew from show business until he died in his own home on Sarandí 334.